1. Field of the Invention
This invention relates to an oil well pump traveling valve mechanism operated from the surface of the earth through its connection with a vertically reciprocating sucker rod string which prevents the development of a gas lock condition in the pump.
In pumping oil wells, virtually all of the oil includes a quantity of natural gas in solution. During a typical pumping operation, the fluid medium of the well undergoes substantial pressure changes, and these pressure changes tend to allow the gas in solution to become liberated from the liquid constituents of the fluid medium, and the liberated gas may interfere with pumping operations. For example, the fluid medium of a well prior to entering the tubing string or pumping chamber of the well is subjected to a pressure known as "bottom hole pressure." This bottom hole pressure relates to the inherent pressure of the production formation and to the hydrostatic head of the fluid medium within the well bore. In typical oil wells that require pumping, there is provided a pair of spaced ball seat valves with the pump piston being positioned above the lowermost ball seat valve.
Where the well pump includes a stationary valve ball and seat, a traveling valve ball and seat is movable relative to the stationary valve. The variable volume between the ball and seat of the stationary and traveling valves constitutes the pumping chamber. A condition of gas-lock will occur when an excessive amount of gas collects within the pumping chamber and the pressure developed by the hydrostatic head of liquid above the ball and seat of the traveling valve is equal to or greater than the pressure of the compressed gas within the pumping chamber in the compression stroke, and when the pressure within the pumping chamber during the vacuum stroke is equal to the bottom hole pressure of the well.
The presence of gas in the fluid also causes "valve chatter" which is destructive of seats and balls of ball check valves. Valve chatter caused by gas also decreases the efficiency of the pump due to improper closing of the ball valves with their seats. It is of course very desirable to provide a traveling oil pump valve mechanism that is capable of efficiently lifting well fluid, including oil, to the surface and which is also effective to prevent the development of a gaslock condition during pumping.
Accordingly, the present invention provides a novel traveling oil pump valve mechanism that serves as the traveling valve mechanism of a spaced valve pumping system and which automatically provides for venting liberated gas into the tubing string for production along with the liquid medium that is pumped from the well.
2. Description of the prior art
Prior patents attempting to eliminate gas-lock and fluid pound conditions in an oil well pump have generally disclosed telescoping sleeves having mating and mismating ports therein which generally provide an increase in the fluid flow from the pump against the static head of oil in the tubing.
The most pertinent prior patent is believed U.S. Pat. No. 1,614,000 which discloses a traveling valve and seat secured to the depending end of a sucker rod string and enclosed within a shell diametrically equal with the pump barrel and when coaxially aligned therewith in the bottom of an oil well permits the traveling valve and its seat assembly to enter and be reciprocated within the bore of the working barrel.
This invention is distinctive over the above named patent and other devices presently in use by interposing a pump head and outer sleeve between an oil well pump working barrel and the sucker rod string. An inner sleeve secured to the pump head contains a tethered ball valve and seat positively moved to open and closed position by sucker rod movement.